Method for laying a cable beneath a slab

Details Method for laying a cable beneath a slab Method for laying a cable beneath a slab

2000-09-01

2001-07-17

Hail, III, Joseph J. (Department: 3723)

Implements or apparatus for applying pushing or pulling force

Method or apparatus for placement of conductive wire

Conduit snakes

C254S134400

Reexamination Certificate

active

06260826

ABSTRACT:

TECHNICAL DOMAIN
This invention relates to a process for placement of a cable under a slab between two openings passing through the slab, without any human intervention under the slab.
In this case, and throughout this text, the term “cable” refers to any flexible, elementary or complex device such as a rope, an electrical cable and/or optical cable, hose, etc.
The process according to the invention may be used in all cases in which it is required to put a cable into position under a slab between two openings formed in the slab, when human intervention under the slab is impossible. Thus, and solely as an example, a process of this type may be used for a cable placed under a slab for closing off a silo used for long term storage of liquid or solid noxious products such as products with radioactive properties in the nuclear industry.
STATE OF PRIOR ART
As shown diagrammatically in
FIGS. 1 and 2
in the attached drawings, large parallelepiped or cylindrical shaped concrete silos
10
are used for the long term storage of liquid or solid products
12
with dimensions up to, or possibly greater than 10 m. When the stored products are noxious waste, these silos are covered with a thick protective concrete slab
14
.
Collection equipment
16
is used when it is required to pick up waste
12
contained in this type of silo
10
or to work in a specific location inside the silo. For example, this collection equipment may consist of a grab in the case of solid waste or a stirring/pumping unit in the case of liquid waste.
The collection equipment
16
is fixed to the lower end of a lifting cable
18
, the upper end of which is wound around the drum of a lifting winch
20
. This lifting winch
20
is located in a collection cell
22
above the slab
14
in line with an opening
24
, usually formed near the center of the slab
14
.
A blind guide system is also placed under slab
14
so that the collection equipment
16
can also be located vertically in line with the location at which the waste
12
to be picked up or pumped is located.
This blind guide system comprises a guide device
26
on which the lifting cable
18
slides. The guide device
26
is itself positioned and moved in the upper part of the silo
10
by means of at least three positioning cables
28
(four cables are shown in FIG.
2
). One of the ends of each of the positioning cables
28
is fixed onto the guide device
26
. The other end of each cable
28
is wound onto the drum of a positioning winch
30
located above and in line with another opening
32
formed in the slab
14
adjacent to its periphery.
Therefore in this type of guide system, each positioning cable
28
is wound onto a winch
30
, then passes through an opening
32
formed in a peripheral part of the slab
14
and passes under this slab, and is finally fixed on the guide device
26
of the lifting cable
18
.
When a storage silo
10
was not equipped with this type of lifting cable guide system
18
when it was first built, there will be problems in placing the positioning cables
28
under the slab
14
, and these problems have not effectively been solved as yet. They are due to the fact that human intervention inside an existing silo is impossible for safety reasons.
The initial position of the guide device
26
adjacent to the opening
24
formed in the central part of the slab
14
does not cause any particular problems. On the other hand, at the present time there is no known technique for connecting this guide device
26
to the positioning winches
30
placed above the peripheral openings
32
by means of positioning cables
28
. In other words, it is not known how to pass a cable blind under a slab between two openings at a certain distance from each other passing through this slab.
DESCRIPTION OF THE INVENTION
The purpose of this invention is a process capable of placing a cable under a slab between two openings in the slab at a certain distance from each other, blind, in other words without human intervention underneath the slab.
According to the invention, this result is achieved using a process for placement of a cable under a slab between a first and a second opening passing through the slab, characterized by the fact that it comprises the following steps:
lower a cable under the slab through the first opening, and rotate the target towards the second opening;
lower a gun under the slab through the second opening, and rotate the gun towards the target;
fire a projectile from the gun, attached to a cable or a hemp rope that can be connected to a cable, this projectile being caught by the target;
raise the target above the slab through the first opening, and disconnect the cable or the hemp rope.
The cable may be fixed directly to the projectile when it is sufficiently lightweight to not reduce the precision of firing due to the drag effect. In all other cases, a strong lightweight hemp rope is used that can be attached to the cable afterwards so that the cable is pulled under the slab using the hemp rope.
In one preferred embodiment of the invention, the target comprises a frame supporting a net and the projectile is a harpoon designed to get trapped in this net.
The target is advantageously suspended from a support by a rigid vertical rod. The target is then lowered until the support comes into contact with the upper face of the slab around the first opening.
In order to orient the target, the rod is rotated about itself with respect to the support. More precisely, the target is oriented by making an arrow fixed onto the rod above the slab coincide with a graduation of a fixed horizontal dial placed above the slab and centered on the rod, this graduation indicating the direction of the second hole.
In particular, the target may be lowered by means of a sling connected to a winch located above the first opening.
In the preferred embodiment of the invention, the projectile is loaded onto the gun after the gun is lowered under the slab. More precisely, the gun is loaded through the top by inserting the projectile vertically through a loading duct that passes through the second opening.
In order to prevent any risk of the hemp rope or the cable getting blocked during firing, it is beneficial to unwind the length of the hemp rope or the cable before firing, the length being equal to at least the distance separating the openings starting from a winder placed above the second opening.
The length of the hemp rope or the cable thus unwound before firing fits into a bowl placed under the gun, particularly when there is no liquid above the solid waste, to prevent the cable from getting wet, which would make the firing parameters difficult to control.
In order to rotate the gun into the right direction, it is lowered until it comes into contact with a stop to define a previously adjusted elevation angle, and it is rotated in azimuth by pivoting the gun around a vertical axis through the second opening. In order to determine this orientation in azimuth, a needle fixed on the gun pivot axis above the slab may be made to coincide with a mark on a second dial fixed horizontally above the slab and centered on this pivot axis, this mark indicating the direction of the first hole.
After firing, the target is raised above the slab through the first opening and the hemp rope or the cable is detached from the projectile.
When the projectile is fixed on a hemp rope distinct from the cable to be installed, the other end of the hemp rope is then fixed to a first end of the cable and the hemp rope is pulled through the first opening until the first end of the cable is recovered.
When the cable forms part of a blind guide system that is to be installed in the upper part of an existing storage silo, the other end of the cable is fixed to a winch located above the second opening.


REFERENCES:
patent: 1865113 (1932-05-01), Kiesel
patent: 3034766 (1962-05-01), Hamrick
patent: 3382859 (1968-05-01), Myers
patent: 4382581 (1983-05-01), Wimer et al.
patent: 6003842 (1999-12-01), Hug
patent: 6109595 (2000-08-01), Lecours
Patent Abstracts of Japan, Publication No.: 633057

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